Stainless Steel - The Safe Choice - Euro Inox

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SAFE STAINLESS STEEL 1. A very low nickel release (less than 0.05 µg/cm2 /week at pH 4.5 and 6.6 ) close to the detection limit and which must be considered as harmless according to the European Directive 94/27/EC. This group includes the three low-sulphur stainless steel grades (AISI 430, 304 and 316L). 2. An intermediate nickel release, close to the 0.5 µg/cm2 /week value which is considered as the limit for a positive reaction in already Ni-sensitised persons, following a prolonged contact with skin. This was for the resulphurised grade (AISI 303). Grade AISI 304/1.4301 Domain of passivity Current density Grouping AISI 316L/1.4404 Yes < 1µA/cm2 1 AISI 303/1.4305 No > 1mA/cm2 2 Ni-plated steel No >> 1mA/cm2 3 Table 2: Electrochemical behaviour in a synthetic sweat solution of pH 4.5 at 23°C 3. A high release (75 µg/cm2 /week) which probably will be harmful in case of prolonged contact of the material with skin. The Ni-plated steel belongs to that group. The results of leaching experiments correlate with those from the electrochemical (polarisation) tests which show that in synthetic sweat solutions: 1. The low-sulphur stainless steel AISI 304 and 316L grades (i.e. standard austenitic grades) have excellent corrosion resistance, characterised by the presence of a passive domain. 2. By comparison the resulphurised stainless steel (AISI 303) and Ni-plated steel have poor corrosion resistance. They present no passive domain in this medium of synthetic sweat. From these experiments it can be concluded that there is no corrosion and correspondingly negligible cation migration for AISI 304 and 316L grades. In comparison for AISI 303 grade and even more for the Ni-plated steel the current density is high (more than 1 mA/cm2 ) indicating an active state and consequently cation migration. The result of electrochemical investigations are summa-rised in Table 2. Results of clinical patch tests clearly show that standard austenitic stainless steel (AISI 304/1.4301 and 316L/1.4404) and the ferritic grade (AISI 430/1.4016 : Ni-free 17 % Cr) stainless steel are harmless since no allergic reaction was seen on the 50 already Nisensitised persons. In contrast, the resulfurised austenitic stainless steel (AISI 303/1.4305) induces allergic reaction for a few persons (14 %) and the Ni-plated steel for nearly all the persons (96 %). The correlation between leaching experiments, electrochemical investigations and clinical patch test validate the value of 0.5 µg/cm2 /week as a limit of nickel release in a synthetic sweat solution. Table 3 summarises the situation. © Euro Inox 2002 www.euro-inox.org · 6
Grade Corrosion resistance Ni release in Clinical test Grouping (passivity) synthetic (allergic sweat reactions) AISI 430/1.4016 AISI 304/1.4301 (µg/cm2/week) (%) AISI 316L/1.4404 Yes < 0.05 0 1 AISI 303/1.4305 Weak ≈ 0.5 14 2 Ni-plated steel No > 70 96 3 5.2 Stainless steels in contact with food Stainless steel plays a vital role in the production and processing of food and beverages. For over 70 years stainless steel has been used in the preparation, processing and transport of food products to ensure a high standard of quality. It does not affect the taste of food and drink. Stainless steel has a high resistance to cleaning agents, disinfectants and sterilising agents such as pressurised steam. Chromium and nickel release from stainless steel in contact with food or during its processing, storage and during meal preparation and cooking is, in most cases, negligible. Experiments on pick-up of chromium and nickel from stainless steel utensils have been conducted using acid fruit (14). Experiments using AISI 430Ti/1.4510 and AISI 444/1.4521 (ferritic grades) and AISI 304/1.4301 (austenitic grade) in a boiling acetic acid solution showed that chromium and nickel release is very low. The concentration observed were close to the detection limits i.e. 30 µg/l for chromium and 10 µg/l for nickel. A recent field investigation (15) of actual operation using meals cooked in glass, ferritic (AISI 436/1.4526) and austenitic (AISI 304/1.4301) stainless steel pans showed that the levels of nickel and chromium fall either within or very close to the range of chromium and nickel reported in the literature. Statistical tests showed that nickel and chromium intake from meals cooked in stainless steel utensils (in austenitic 18.2 % Cr - 8.6 % Ni/304 grade and in ferritic 16.6 % Cr - 1.0 % Mo niobium stabilised/436 grade) was insignificant. It is clear that the use of stainless steel cooking utensils does not provide a significant source of dietary chromium or nickel and there is no advantage to be gained by nickel-sensitive persons who suffer from contact allergy by avoiding the use of stainless steel utensils. SAFE STAINLESS STEEL Table 3: Stainless steel in prolonged contact with skin and the Ni contact dermatitis issue. © Euro Inox 2002 www.euro-inox.org · 7
Page 1 and 2: Editorial Stainless Steel - The Saf
Page 3 and 4: 4. The essential character of metal
Page 5: Consequently, most metallic alloys
Page 9 and 10: • Titanium is added to the ferrit
Page 11: 12) Haudrechy P, Foussereau J, Mant

Stainless Steel - The Safe Choice - Euro Inox

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